The study is dedicated to contradictions A = to A in Russian, also known in literature as 'negated tautologies'. They are often viewed as derivations from equative tautologies A = A. Here I describe structural and semantic features of negated tautologies that are established in Russian with patterns X ne X 'X is not X', X ne est' X 'X is not X' and X - eto ne X 'X this is not X'. Such constructions show that the speaker is not able to use the corresponding tautology X is X because (a) the referent of a linguistic expression X does not belong to the category X; (b) characteristics of the referent of a linguistic expression X or an attitude towards it differ from the norm; (c) the linguistic expression X is not employed in its common, straight meaning. Besides, negated tautologies are compared to similar Russian constructions S_dat + X ne X₂ 'S_dat + X is not X' and X ne v X2 'X is not in X', and to tautologies X est' X 'X is X' and X - eto X 'X this is X'.